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mikebamber asked

MultiPlus ii Parallel Question

Hi, currently running an MPii with 4x Pylontech US2000s. Everything is great. I don't use the AC out, it's running as a grid tie ESS. Using solar too on the AC side.

What I want to do is add a second Multiplus with a different type of battery (thinking EVE LiFePo4 cells and Batrium BMS).

If this works then I can scale the system up over time with more MPs.

Is this feasible? or do both the multiplusses need to be connected to the same battery?

multiplus in parallel
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mikebamber avatar image mikebamber commented ·
Am I overthinking this? Can I just add more Multiplus devices to the AC IN supply, hook them all up to the Cerbo and they'll be happy?
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Alexandra answered ·

@mikebamber

If they are being programmed as parallel then they share a battery bank.

There is some more documents and information linked in the related resources box on this page - to the right on laptop - to the bottom on mobile.

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mvas answered ·

How does the existing MultiPlus know when it is OK to recharge the battery bank? Time of day? Do you have TOU electric rates?

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mikebamber avatar image mikebamber commented ·

I manually schedule charge time, also the battery charges from surplus solar.

So can you confirm that the proposed system is OK? Would they operate effectively as a master unit and 'see' two batteries?

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Alexandra avatar image Alexandra ♦ commented ·

It is a requirement for Victron - it is in the manual.

if there is a voktage difference - if there is an amp difference - they will perform differently and not load share.

There is if they they do not share the load equally one bank will deplete faster than the other - one unit will then shut down before the other and then you will see errors on the GX - for example error 3
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mvas avatar image mvas Alexandra ♦ commented ·

What "load sharing" are you talking about? There is no load on AC OUT.

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mikebamber avatar image mikebamber Alexandra ♦ commented ·
So I'm not sure if it's relevant to your reply @Alexandra but I'm not using the AC out, just using AC in in a grid-tie config.


@mvas yes I'm on a TOU electric tariff but also I have a lot of solar panels.

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mvas avatar image mvas mikebamber commented ·
People may think that your MultiPlus will be sharing a load on AC OUT because you used the word "parallel", as in a "Master / Slave" Parallel configuration, in your title. Are going to enable "Master / Slave" Parallel mode configuration for load sharing? Do you have a Cerbo?
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